This invention relates to apparatus for playing a game, for example, bingo, in which various symbols in a pattern on a sheet are selectively marked during the game. More particularly, the invention relates to such apparatus in which the symbol-carrying structure may be unitary and may function without the necessity for any additional unconnected pieces of apparatus.
Conventionally, in games in which symbols on a sheet are to be selectively marked during the game, this function has been provided either by placing additional objects, such as button-like structures, atop the symbols to be marked, or by use of a marking instrument, such as a pencil, to mark the selected symbol. The former of these structures has suffered from the obvious disadvantage of the requirement of numerous separate button-like pieces to place above the symbols, which pieces are bulky to package and subject to loss over the life of the game apparatus. The latter of the conventional structures has suffered from the disadvantages of both requiring a marking instrument, which is also subject to loss, exhaustion or damage, and of causing defacement of the sheets bearing the symbols, thus requiring their replacement.
In recent years a structure known popularly as a "magic slate" has become popular for providing a renewable surface for drawing or writing. This device includes a transparent top sheet of clear plastic, an intermediate sheet of a translucent plastic material, and a backing member of rigid cardboard, coated with transparent wax-like substance over a dark background. Marks are made on this structure by pressing and moving a stylus against the transparent top sheet urging it against the translucent sheet and the translucent sheet against the waxy material. The portions of the translucent sheet are forced into firm contact with the waxy material so that the dark background behind the waxy material shows through the waxy material and the translucent and transparent sheets in those areas, thus providing a representation of the figure drawn or written onto the structure. When it is desired to renew the surface for additional use, the translucent sheet is simply lifted free of its contact with the waxy backing material, so that it then provides a fresh, unmarked, translucent surface for additional drawing or writing.